The overall objective of this proposal is to establish a centralized Flow Cytometry Facility at Roswell Park Memorial Institute through the purchase of one laser-based flow cytometer with ancillary equipment and the upgrading of an existing instrument. This equipment will be utilized by a number of investigators from clinical and basic science departments for projects involving the common theme of toxicological effects on individuals and/or cells exposed to therapeutic agents of biological and chemical origin as well as x-irradiation. As described, the Flow Cytometer Facility will comprise two instruments: 1) a dual laser cell sorter with complete data reduction capability capable of sorting chromosomes, cells and other particles, and 2) a second laser-based FACS-II for cell sorting, currently owned by Roswell Park Memorial Institute and for which computer upgrading is requested. Together these instruments will enable the investigators named to perform state-of-the-art analysis on the effects of toxicological, pharmacological and viral pathogens in terms of induced chromosomal aberrations, DNA/RNA ploidy index and abnormal cell cycle kinetics, alteration in surface antigen distribution and viral receptors, and, through development of chromosome "library", isolation and characterization of viral oncogenes of critical importance for latent tumorigenesis. Finally, the requested instrumentation will be utilized to sequentially analyze the effects of total body x-irradiation on DNA/RNA content, cell cycle and surface antigen kinetics of bone marrow and peripheral blood cells in patients undergoing autologous and allogeneic bone marrow transplantation.